Production of optically active phospholanes

ABSTRACT

Phospolanes and diphospholanes of the general formula Iwhere:&lt;/PTEXT&gt;is H, C&lt;HIL&gt;&lt;PDAT&gt;1&lt;/SB&gt;&lt;PDAT&gt;-C&lt;HIL&gt;&lt;PDAT&gt;6&lt;/SB&gt;&lt;PDAT&gt;-aryl, alkylaryl, SiR&lt;HIL&gt;&lt;PDAT&gt;3&lt;/SB&gt;&lt;HIL&gt;&lt;2&lt;/SP&gt;&lt;PDAT&gt;,&lt;/PTEXT&gt;R&lt;HIL&gt;&lt;2 &lt;/SP&gt;&lt;PDAT&gt;is alkyl or aryl,&lt;/PTEXT&gt;A is H, C&lt;HIL&gt;&lt;PDAT&gt;1&lt;/SB&gt;&lt;PDAT&gt;-C&lt;HIL&gt;&lt;PDAT&gt;6&lt;/SB&gt;&lt;PDAT&gt;-alkyl, aryl, Cl orB is a linker with 1-5 C atoms between the two P atoms, and their use as catalyst in asymmetric synthesis.&lt;/PTEXT&gt;

This application is a 371 of PCT/E99/03702 filed May 28, 1999 , now WO99/62917.

The invention describes novel optically active phospholanes andbisphospholanes, the preparation thereof and use thereof as ligands inmetal complexes, and the use of the metal complexes for enantioselectivesynthesis.

Enantioselective hydrogenation and isomerization with rhodium andruthenium complexes is very important in the synthesis of opticallyactive compounds (e.g. Tani et al. J. Am. Chem Soc 106, 5211, 1984; R.Noyori, Acc. Chem. Res. 23, 345 (1990). The stoichiometric startingmaterial hydrogen costs little, but the catalysts employed, which aremostly prepared from an optically active diphosphine ligand and arhodium or ruthenium compound, are very costly and can be obtained onlyin a complicated manner.

The known methods for preparing optically active phosphines anddiphosphines are all complicated and usually include a technicallyelaborate and costly racemate resolution (e.g. EP-A 0614901; EP-A0271311; H. B. Kagan, “Chiral Ligands for Asymmetric Catalysis” inAsymmetric Synthesis, Vol. 5 (1985), pages 13-23, EP-A 0151282; EP-A0185882; R. Noyori, Acc. Chem. Res. 23, 345 (1990); EP-269395; M. J.Burk, Tetrahedron, Asymmetry, pages 569-592 (1991); J. Am. Chem. Soc.113, pages 8518-9 (1991), ibid. 115, pages 10125-138 (1993), ibid. 117,pages 9375-76 (1995), ibid 118, page 5142 (1996)). These disadvantagesmake industrial use difficult and uneconomic.

It is an object of the present invention to provide phosphine ligandswhich can be prepared easily and at low cost and which are good ligandsfor metal complex catalysts for enantioselective synthesis.

We have found that this object is achieved by a particularly efficientclass of ligands, mainly phospholanes, which can be obtained from the“chiral pool”. The starting material is in this case mannitol and othercarbohydrates which can be obtained in large quantities at low cost.

The resulting phospholanes and diphospholanes provide excellentenantiomeric excesses in asymmetric hydrogenations. The known DUPHOSligands of Burk et al. (M. J. Burk, Tetrahedron, Asymmetry, pages569-592 (1991); J. Am. Chem. Soc. 113, pages 8518-9 (1991), ibid. 115,pages 10125-138 (1993), ibid. 117, pages 9375-76 (1995), ibid 118, page5142 (1996); U.S. Pat. No. 5,008,457; WO 92/19630; WO 93/19040) are verymuch more elaborate to synthesize, in contrast to the present invention.Synthesis of the DUPHOS ligands requires, inter alia, an impracticalelectrolytic Kolbe synthesis in addition to an asymmetric hydrogenation.

The present invention avoids these difficulties by using the sugarmannitol which can be obtained enantiomerically pure from naturalsources. In addition, this precursor provides a route to compounds whichhave alkoxymethyl or hydroxymethyl groups in positions 2 and 5 in thephospholane ring. Compounds of this type cannot be prepared by the knownDUPHOS synthesis.

The invention relates to phospholanes and diphospholanes of the generalformula I

where:

R is H, C₁-C₆-alkyl, aryl, alkylaryl, SiR₃ ²,

R² is alkyl or aryl,

A is H, C₁-C₆-alkyl, aryl, Cl or

B is a linker with 1-5 C atoms between the two P atoms.

Preferred substituents R are hydrogen, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, benzyl, trityl andtrialkylsilyl or triarylsilyl (SiR₃ ² where R²=C₁-C₆-alkyl or aryl).

In the case of the diphospholanes, those which are preferred have

with n=0, 1, 2, 3, 4

Particularly preferred linkers B are those where n is 1 or 2 and m is 0.

The invention further relates to metal complexes comprising theabovementioned phospholanes with central atoms from the group of Rh, Ru,Ir, Pd, Pt, Ni.

Particularly preferred metal complexes are those which contain rutheniumor rhodium as central atom.

These complexes can be prepared by synthesizing the catalytically activecomplexes in a known manner (e.g. Uson, Inorg. Chim. Acta 73, 275(1983), EP-A 0158875, EP-A 437690) by reacting with rhodium, iridium,ruthenium, palladium, platinum or nickel complexes which contain labileligands (e.g. [RuCl₂(COD)]_(n), Rh(COD)₂BF₄, Rh(COD)₂ClO₄, [Ir(COD)Cl]₂,p-cymene-ruthenium chloride dimer).

The invention further relates to the use of these metal complexes inasymmetric synthesis, especially as catalyst for hydrogenations,hydroformylations, hydrocyanations, allylic substitutions andisomerizations of allylamines to enamines.

These reactions can be carried out with the metal complexes according tothe invention under conditions familiar to the skilled worker.

The hydrogenation with the metal complexes according to the invention isusually carried out at a temperature from −20 to 150° C., preferably at0 to 100° C. and particularly preferably at 15 to 40° C.

The pressure of hydrogen for the hydrogenation process according to theinvention can be varied in a wide range between 0.1 bar and 300 bar.Very good results are obtained with a pressure in the range from 1 to10, preferably 1 to 2 bar.

It is particularly advantageous with the ligands according to theinvention that the hydrogenations can be carried out very efficiently atthe low pressure of 1 to 2 bar of hydrogen.

Preferred solvents for the hydrogenations are C₁-C₄-alkanols, especiallyMeOH. In the case of substrates of low solubility, solvent mixtures,e.g. methanol and CH₂Cl₂ or THF, toluene are also suitable.

The catalyst is normally employed in amounts of from 0.001 to 5 mol %,preferably 0.001 to 0.01 mol %, based on the substrate to behydrogenated.

EXAMPLE 1 Experimental Part

The method of E. J. Corey et al.¹ was used to react1,2;5,6-di-O-isopropylidene-D-mannitol with thiophosgene in the presenceof 4-dimethylaminopyridine in methylene chloride with a yield of 90%.

E-3,4-Didehydro-3,4-dideoxy-1,2;5,6-di-O-isopropylidene-D-threo-hexitol(2)

Heating the cyclic thiocarbonate 1 in triethyl phosphite for 20 hours inaccordance with the literature^(2,3) resulted in the trans-olefin inyields of 80 to 90%.

3,4-Dideoxy-1,2;5,6-di-O-isopropylidene-D-threo-hexitol (3)

In a modification of the method of Machinaga et al.⁴, the olefin 2 (10g) was hydrogenated in methanol with 10% platinum on active carbon (250mg) under atmospheric pressure to give compound 3. After purification bycolumn chromatography, the yield was 80 to 90%. Compound 3 can also bepurified by distillation in accordance with the literature⁴ (boilingpoint 0.6 mm=73° C.).

3,4-Dideoxy-D-threo-hexitol (4)

Acid hydrolysis of the isopropylidene groups took place in 1Nhydrochloric acid in accordance with the literature⁴. The compound wasobtained in a yield of 85% after recrystallization.

(2S,5S)-1,6-Bis(benzyloxy)-2,5-hexanediol (5)

3.0 g (20 mmol) of 3,4-dideoxy-D-threo-hexitol (4) was converted by themethod of Marzi et al.⁵ into 3.70 g of the 1,6-di-O-benzylated product 5in a yield of 56%.

(2S,5S)-1,6-Bis(tert-butyldiphenylsilyloxy)-2,5-hexanediol (6)

3.0 g (20 mmol) of compound 4 were reacted withtert-butyldiphenylchlorosilane in DMF in the presence of imidazole basedon the literature⁵ gives the derivative 6 in a yield of 80%.

(4S,7S)-4,7-Bis(benzyloxymethyl)-2,2-dioxo[1,3,2]dioxathiepane (7)

1.43 g (12 mmol) of thionyl chloride were slowly added to 3.30 g (10mmol) of the diol 5 in 70 ml of dry tetrachloromethane under an argonatmosphere, and the mixture was then refluxed for 90 minutes. Afterremoval of the solvent in a rotary evaporator, the residue was taken upin a mixture of tetrachloromethane (40 ml), acetonitrile (40 ml) andwater (60 ml) and, at 0° C., 15 mg (72 μmol) of RuCl₃*3H₂O and 4.28 g(20 mmol) of sodium periodate were added. The mixture was then left tostir at room temperature for one hour, and then 50 ml of water wereadded to the suspension. Subsequent extraction with diethyl ether (3×75ml) and washing of the organic phase with saturated NaCl solution (100ml), followed by drying (Na₂SO₄), resulted in a residue which on columnchromatography (n-hexane:AcOEt=2:1, R_(f)=0.20) afforded compound 7 in ayield of 3.37 g (86%).

Melting point=57 to 59° C.; [α]D²⁶=−37.2° (c 1.01; CHCl₃); ¹H-NMR(CDCl₃, 400 MHz) δ7.34 (10H, m, arom. H), 4.78 (2H, m, H-2/5), 4.57 (2H,AB sp., H_(a)-CH₂Ph, ²J_(a,b)=12.0 Hz) , 4.56 (2H, AB sp., H_(b)-CH₂Ph,²J_(a,b)=12.0 Hz), 3.65 (2H, dd, H_(a)-CH₂OH, ²J_(a,b)=10.8 Hz,³J_(H,H)=5.4 Hz), 3.56 (2H, dd, H_(b)-CH₂OH, ²J_(a,b)=10.8 Hz,³J_(H,H)=4.9 Hz), 2.00 (4H, m, H-3/4); ¹³C-NMR (CDCl₃, 100 MHz) δ137.3,128.4-127.7 (arom. C), 82.6 (C-2/5), 73.4 (CH₂Ph), 70.8 (C-1/6), 28.9(C-3/4); elemental analysis C₂₀H₂₄O₆S (392.47) calc.: C, 61.21; H, 6.16;S, 8.17; found: C, 61.03; H 6.19; S 8.10;

1,6-Di-O-(tert-butyldiphenylsilyl)-2,5-O-isopropylidene-3,4-dideoxy-D-threo-hexitol(8)

6.27 g (10 mmol) of compound 6 were converted into the isopropylidenederivative 8 in a yield of 85% (5.67 g) in accordance with theliterature⁵. 8 was purified for characterization by columnchromatography (n-hexane: diethyl ether=19:1, R_(f)=0.2). Purificationof the compound was unnecessary for the next reaction step.

2,5-O-Isopropylidene-3,4-dideoxy-D-threo-hexitol (9)

Elimination of the silyl groups from 6.67 g (10 mmol) of the silylcompound 8 with tetrabutylammonium fluoride in THF⁵ and subsequentpurification by chromatography (diethyl ether:MeOH=19:1, R_(f)=0.5)resulted in 1.7 g (89%) of diol 9.

2,5-O-Isopropylidene-1,6-di-O-methyl-3,4-dideoxy-D-threo-hexitol (10)

A solution of 3.80 g (20 mmol) of the diol 9 in 30 ml of THF was addedat 0° C. to a solution of 1,06 g (44 mmol) of NaH in 60 ml of THF. Afterthe alcoholate formation was complete, 2.2 equivalents of methyl iodide(6.21 g, 44 mmol) were slowly added, and the mixture was stirred at roomtemperature. After completion of the reaction, the excess NaH wascautiously destroyed with water (30 ml), and the THF was removed invacuo. The remaining aqueous solution was then extracted with methylenechloride (3×50 ml), and the combined organic phase was dried (Na₂SO₄).The residue obtained after concentration afforded, after columnchromatography (n-hexane:AcOEt=2:1, R_(f)=0.40), a colorless syrup in ayield of 84% (3.68 g).

Syrup; [α]D²³=−32.8° (c 1.01, CHCl₃); ¹H-NMR (CDCl₃, 400 MHz) δ3.92 (2H,m, H-2/5), 3.32 (2H, dd, H_(a)-CH₂O, ²J_(a,b)=9.9 Hz, ³J^(H,H)=6.3 Hz),3.30 (6H, s, CH₃), 3.55 (2H, m, H_(b)-CH₂O, ²J_(a,b)=9.9 Hz,³J_(H,H)=5.3 Hz), 1.67 (2H, m, H_(a)-3/4), 1.34 (2H, m, H_(b)-3/4), 1.31(6H, s, CH₃); ¹³C-NMR (CDCl₃, 100 MHz) δ100.5 (C(O)₂), 76.2 (C-1/6),70.4 (C-2/5), 59.1 (CH₃), 31.1 (C-3/4), 25.6 (C(CH₃)₂); elementalanalysis C₁₁H₂₂O₄ (218.293) calc.: C, 60.52; H, 10.16; found: C, 60.38;H, 10.07;

(2S,5S)-1,6-Bis(benzyloxy)-2,5-hexanediol (11)

4.0 g (18.32 mmol) of compound 10 were hydrolyzed in a mixture of 60 mlof THF and 60 ml of 1N hydrochloric acid in 20 minutes. After thesolution had been concentrated in a rotary evaporator it ischromatographed (EtOH:AcOEt=1:3, R_(f)=0.45) to result in 3.20 g of apale yellow syrup 11 in almost quantitative yield.

Syrup; [α]D²²=−7.2° (c 1.09, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ3.72 (2H,m, H-2/5), 3.37 (6H, s, CH₃), 3.38-3.30 (4H, m, CH₂OH), 1.56 (4H, m,H-3/4); ¹³C-NMR (CD₃OD, 100 MHz) δ78.2 (C-1/6), 70.1 (C-2/5), 59.2(CH₃), 30.6 (C-3/4); elemental analysis C₈H₁₈O₄ (178.228) calc.: C,53.91; H, 10.18; found: C, 53.47; H, 10.14;

(4S,7S)-4,7-Bis(methyloxymethyl)-2,2-dioxo[1,3,2]dioxathiepane (12)

1.78 g (10 mmol) of the diol 11 were converted into the target compound12 in analogy to the preparation of the cyclic sulfate 7. It waspossible to dispense with purification by chromatography(n-hexane:AcOEt=1:2, R_(f)=0.4) in this case because the product 12could be isolated by crystallization from diethyl ether/n-hexane as awhite solid in a yield of 76% (1.83 g).

Melting point=75-78° C.; [α]D²³=−44.1° (c 1.01; CHCl₃); ¹H-NMR (CDCl₃,400 MHz) δ4.72 (2H, m, H-2/5), 3.56 (2H, dd, H_(a)-CH₂O, ²J_(a,b)=10.8Hz, ³J_(H,H)=5.4 Hz), 3.47 (2H, dd, H_(a)-CH₂O, ²J_(a,b)=10.8 Hz,³J_(H,H)=4.7 Hz), 3.37 (6H, s, CH₃), 2.04-1.92 (4H, m, H-3/4); ¹³C-NMR(CDCl₃, 100 MHz) δ82.5 (C-2/5), 73.4 (C-1/6), 59.3 (OCH₃), 28.8 (C-3/4);elemental analysis C₈H₁₆O₆S (240.274) calc.: C, 39.99; H, 6.71; S,13.34; found: C, 40.06; H, 6.76; S, 1.27;

1,2-Bis[(2R,5R)-2,5-benzyloxymethylphospholanyl]benzene(13)

2.0 equivalents of n-BuLi (4.58 ml, 1.6 M solution in n-hexane) wereslowly added to 0.52 g (3.66 mmol) of 1,2-bis(phosphinyl)-benzene in 50ml of THF and, after 2 hours, 2.86 g (7.32 mmol) of the cyclic sulfate 7in 20 ml of THF were added slowly to the resulting yellow solution. Themixture was stirred at room temperature for a further 2 hours and,finally, 2.2 equivalents of n-BuLi (5.03 ml, 1.6 M solution in n-hexane)were again added. The solution was stirred overnight, and excess BuLiwas finally destroyed with 2 ml of MeOH. The solvent was removed invacuo, and the residue was taken up with 20 ml of water under anaerobicconditions and then extracted with methylene chloride (2×50 ml). Afterdrying the organic phase (Na₂SO₄) and removing the solvent, the requiredproduct was isolated by column chromatography (n-hexane:AcOEt=4:1,R_(f)=0.35) in a yield of 0.52 g (19%) as a pale yellow syrup.

Syrup; ¹H-NMR (CDCl₃, 400 MHz) δ7.45-7.10 (24H, m, arom. H), 4.49 (2H,AB sp., H_(a)-CH₂Ph, ²J_(a,b)=12.1 Hz), 4.47 (2H, AB sp., H_(b)-CH₂Ph,²J_(a,b)=12.1 Hz), 4.18 (2H, AB sp., H_(a)-CH₂Ph, ²J_(a,b)=11.9 Hz),4.04 (2H, AB sp., H_(b)-CH₂Ph, ²J_(a,b)=11.9 Hz), 3.65-3.45 (4H, m,CH₂O), 2.97-2.80 (4H, m, CH₂O), 2.70 (2H, m, CH-P); 2.33 (4H, m, CH-P,H_(a)-(CH₂)₂); 2.18 (2H, m, H_(a)-(CH₂)₂), 1.80-1.53 (4H, m,H_(b)-(CH₂)₂); ¹³C-NMR (CDCl₃, 100 MHz) δ141.8 (m, C_(ar)-P),138.6+138.5 (ipso-C), 131.8, 128.4-127.1 (arom. C), 74.1 (m, CH₂Ph),73.0 (CH₂Ph), 72.5 (CH₂O), 72.5 (CH₂O), 39.5 (CH-P), 38.9 (m, CH-P),30.9 (CH₂), 30.4 (CH₂); ³¹P-NMR (CDCl₃, 162 MHz) δ11.5;

1,2-Bis[(2R,5R)-2,5-methyloxymethylphospholanyl]benzene(14)

In analogy to the preparation of bisphospholane 13, the compound 12 wasreacted in place of the cyclic sulfate 7 to give the requiredmethoxymethyl-substituted bisphospholane 14. Purification and isolationtook place by column chromatography (n-hexane:AcOEt=2:1, R_(f)=0.20) ina yield of 0.80 g (48%) of the colorless syrup.

Syrup; ¹H-NMR (CDCl₃, 400 MHz) δ7.45 (2H, m, arom. H), 7.30 (2H, m,arom. H), 3.55 (4H, m, CH₂O), 3.36 (2H, m, CH₂O), 3.35 (6H, s, CH₃),3.10 (6H, s, CH₃), 2.90 (2H, m, CH₂O), 2.78 (2H, m, CH-P), 2.63 (2H, m,CH-P), 2.32 (2H, m, CH₂); 2.16 (4H, m, CH₂); 1.68 (2H, m, CH₂), 1.55(4H, m, CH₂); ¹³C-NMR (CDCl₃, 100 MHz) δ141.9 (m, C_(ar)-P), 131.8,128.4 (arom. C), 74.1 (m, CH₂Ph), 76.6 (m, CH₂O), 74.5 (CH₂O), 58.8(CH₃), 58.2 (CH₃), 39.6 (CH-P), 39.0 (m, CH-P), 30.9 (CH₂), 30.3 (CH₂);³¹P-NMR (CDCl₃, 162 MHz) δ−11.7;

1,2-Bis[(2R,5R)-2,5-benzyloxymethylphospholanyl]ethane borane complex(15)

7.40 mmol (4,63 ml) of a 1.6 M n-BuLi solution in hexane were added to348 mg (3.70 mmol) of bis(phosphinyl)ethane in THF at room temperature,and the mixture was stirred for two hours. Then a solution of 2.90 g(7.40 mmol) of the cyclic sulfate 7 in 20 ml of THF was slowly added,and the mixture was stirred for a further two hours. Subsequent additionof a further 5.09 ml (8.14 mmol) of n-BuLi solution completed thereaction after stirring overnight. To form the borane adduct, thesolution was cooled to −20° C. and 9.25 ml (9.25 mmol) of a 1M BH₃*THFsolution were added. After two hours, excess BuLi and BH₃ were destroyedby adding 2 ml of MeOH, and the solvent was removed in vacuo. Theresidue was taken up in water and then extracted with methylenechloride. The extracts were then dried (Na₂SO₄) and concentrated, andthe residue was purified by column chromatography (n-hexane: AcOEt=4:1,R_(f)=0.20). 350 mg (13%) of a viscous syrup were obtained.

Syrup; ¹H-NMR (CDCl₃, 400 MHz) δ7.37-7.22 (20H, m, arom. H), 4.47 (2H,AB sp., H_(a)-CH₂Ph, ²J_(a,b)=11.2 Hz), 4.42 (2H, AB sp., H_(a)-CH₂Ph,²J_(a,b)=12.1 Hz), 4.41 (2H, AB sp., H_(b)-CH₂Ph, ²J_(a,b)=12.1 Hz),4.38 (2H, AB sp., H_(b)-CH₂Ph, ²J_(a,b)=11.2 Hz), 3.58 (4H, m, CH₂O),3.43 (4H, m, CH₂O), 2.37 (2H, m, CH-P); 2.14-1.79 (10H, m, CH-P,(CH₂)₂), 1.41-1.20 (2H, m, (CH₂)₂), 0.85-0.00 (6H, m, BH₃); ¹³C-NMR(CDCl₃, 100 MHz) δ138.1+137.9 (ipso-C), 128.3-127.4 (arom. C), 73.2(CH₂Ph), 72.7 (CH₂Ph), 69.4 (CH₂O), 68.4 (CH₂O), 39.5 (m, CH-P), 29.1(CH₂), 28.6 (CH₂), 15.9 (m, CH₂)₂); ³¹P-NMR (CDCl₃, 162 MHz) δ40.2;

1,2-Bis[(2R,5R)-2,5-methyloxymethylphospholanyl]ethane borane complex(16)

2.14 g (8.91 mmol) of cyclic sulfate 12 and 0.42 g (4.45 mmol) ofbis(phosphinyl)ethane were reacted in analogy to the preparation ofcompound 15 to give the required borane-protected bisphospholane 16.Purification by chromatography took place with n-hexane:AcOEt=2:1(R_(f)=0.15). A crystalline product was obtained in a yield of 0.71 g(39%).

Melting point=45-48° C.; [α]_(D) ²³=21.9° (c 1.00; CHCl₃); ¹H-NMR(CDCl₃, 400 MHz) δ3.51 (8H, m, CH₂O), 3.33 (6H, s, CH₃O), 3.32 (6H, m,CH₃O), 2.36 (2H, m, CH-P); 2.23-2.05 (6H, m, CH-P, (CH₂)₂), 1.96 (4H, m,CH₂)₂), 1.58-1.35 (4H, m, (CH₂)₂), 0.95-0.00 (6H, m, BH₃); ¹³C-NMR(CDCl₃, 100 MHz) δ71.6 (m, CH₂O), 70.8 (CH₂O), 58.7 (CH₃O), 58.7 (CH₃O),39.5 (m, CH-P), 29.1 (CH₂), 28.9 (CH₂), 15.8 (m, CH₂)₂); ³¹P-NMR (CDCl₃,162 MHz): δ40.5; MS (m/z; EI) 391 [M⁺-BH₄] (100);

1,2-Bis[(2R,5R)-2,5-methyloxymethylphospholanyl]ethane (17)

0.30 g (0.42 mmol) of the borane complex 15 were mixed with an anaerobicsolution of 0.142 g (1.26 mmol) of DABCO in 6 ml of toluene and stirredat 40° C. After the reaction was complete, the solution was concentratedand purified by rapid column chromatography (n-hexane:AcOEt=4:1,R_(f)=0.55). The bisphospholane 17 was obtained in a yield of 0.21 g(73%) and was employed immediately for complex formation.

Syrup; ¹H-NMR (CDCl₃, 400 MHz) δ7.35-7.21 (20H, m, arom. H), 4.52 (2H,AB sp., H_(a)-CH₂Ph, ²J_(a,b)=12.1 Hz), 4.48 (2H, AB sp., H_(b)-CH₂Ph,²J_(a,b)=12.1 Hz), 4.43 (2H, AB sp., H_(a)-CH₂Ph, ²J_(a,b)=12.1 Hz),4.41 (2H, AB sp., H_(b)-CH₂Ph, ²J_(a,b)=12.1 Hz), 3.61-3.41 (8H, m,CH₂O), 2.29 (2H, m, CH-P); 2.20 (2H, m, CH-P); 2.07 (4H, m,H_(a)-(CH₂)₂), 1.53-1.23 (8H, m, H_(b)-(CH₂)₂), (CH₂)₂); ¹³C-NMR (CDCl₃,100 MHz) δ138.6+138.4 (ipso-C), 128.3-127.3 (arom. C), 74.2 (m, CH₂Ph),72.9 (CH₂Ph), 72.7 (CH₂O), 70.2 (CH₂O), 43.7 (m, CH-P), 40.0 (m, CH-P),31.4 (CH₂), 31.3 (CH₂), 19.1 (m, CH₂)₂); ³¹P-NMR (CDCl₃, 162 MHz):δ−6.9;

Preparation of the [Rh(COD) (P-P)]BF₄ complexes 18, 19 and 20

0.3 mmol of the bisphospholane ligands 13, 14 and 17 were dissolved in1.5 ml of THF and slowly added at a temperature of −10° C. to asuspension of 0.122 g (0.3 mmol) of [Rh(COD)₂]BF₄ in 3.5 ml of THF.After about 10 minutes, the solution was filtered under anaerobicconditions to remove insoluble constituents, and 15 ml of diethyl etherwere added. This resulted in an orange precipitate or else a brown oilseparating out. Decantation of the supernatant solution and washingtwice with diethyl ether (5 ml) afforded, after drying in vacuo, anorange powder in NMR-spectroscopically pure form. [Rh(COD) (13)]BF₄(18): Yield 225 mg (73%); ¹H-NMR (CDCl₃, 400 MHz) δ7.70-6.80 (24H, m,arom. H), 5.76 (2H, m, CH_(COD)), 4.66 (2H, m, CH_(COD)), 4.42 (2H, ABsp., H_(a)-CH₂Ph, ²J_(a,b)=12.3 Hz), 4.18 (2H, AB sp., H_(b)-CH₂Ph,²J_(a,b)=12.3 Hz), 4.05 (2H, AB sp., H_(a)-CH₂Ph, ²J_(a,b)=12.9 Hz),4.05 (2H, AB sp., H_(b)-CH₂Ph, ²J_(a,b)=12.9 Hz), 3.80 (2H, m, CH₂O),3.60 (4H, m, CH₂O), 3.30 (2H, m, CH₂O), 2.87-1.50 (20H, m, 4xCH-P,4x(CH₂)₂); ¹³C-NMR (CDCl₃, 100 MHz) δ140.5 (m, Car-P), 137.7+137.0(ipso-C), 132.3, 128.5-127.3 (arom. C), 107.0 (CH_(COD)), 91.9(CH_(COD)), 73.2 (m, CH₂Ph), 73.0 (CH₂Ph), 70.6 (m, CH₂O), 68.1 (CH₂O),49.7 (m, CH-P), 42.7 (m, CH-P), 33.7 (CH₂), 32.1 (CH₂), 31.3 (CH₂), 27.0(CH₂); ⁻P-NMR (CDCl₃, 162 MHz): δ64.3 (¹J_(Rh,P)=150 Hz); MS (m/z;FAB_(pos)) 941 [M⁺-BF₄] (20), 833 [M⁺-BF₄-COD] (100);

[Rh(COD)(14)]BF₄ (19): Yield 155 mg (71%); ¹H-NMR (CDCl₃, 400 MHz) δ7.74(2H, m, arom. H), 7.68 (2H, m, arom. H), 5.57 (2H, m, CH_(COD)), 4.80(2H, m, CH_(COD)), 3.82 (2H, m, CH₂), 3.67 (2H, m, CH₂), 3.50 (2H, m,CH₂), 3.26 (6H, s, CH₃O), 3.13 (2H, m, CH₂), 2.90 (2H, m, CH-P), 2.85(6H, s, CH₃O), 2.67-2.27 (14 H, m, CH-P, (CH₂)₂), 1.94 (2H, m, (CH₂)₂),1.58 (2H, m, (CH₂)₂);¹³C-NMR (CDCl₃, 100 MHz) δ140.2 (m, C_(ar)-P),132.4-132.0 (arom. C), 106.1 (m, CH_(COD)), 90.8 (m, CH_(COD)), 73.7 (m,CH₂O), 70.8 (CH₂O), 58.8+58.7 (CH₃O), 49.4+42.5 (m, CH-P),33.5+31.9+31.2+27.6 (CH₂); ³¹P-NMR (CDCl₃, 162 MHz): δ65,0(¹J_(Rh,P)=150 Hz);

[Rh(COD) (17)]BF₄ (20): Yield 190 mg (65%); ¹H-NMR (CDCl₃, 400 MHz)δ7.30-7.05 (20H, m, arom. H), 5.55 (2H, m, CH_(COD)), 4.58 (2H, m,CH_(COD)), 4.43-4.20 (8H, m, CH₂Ph, 3.77-3.40 (8H, m, CH₂O), 2.50-1,90(20H, m, CH-P, (CH₂)₂); 1.60-1.20 (4H, m, (CH₂)₂); ¹³C-NMR (CDCl₃, 100MHz) δ137.9+137.7 (ipso-C), 128.5-127.2 (arom. C), 102.1 (CH_(COD)),91.5 (CH_(COD)), 73.4+72.1 (CH₂Ph), 72.8 (CH₂O), 68.8 (CH₂O), 45.2+39.2(m, CH-P), 32.7 (CH₂), 31.3 (CH₂), 30.0 (CH₂), 27.7 (CH₂) 20.8 (m,CH₂)₂); ³¹P-NMR (CDCl₃, 162 MHz): δ7. 3 (¹J_(Rh,P)=147 Hz);

References

¹ E. J. Corey; P. B. Hopkins Tetrahedron Lett. 23 (1982) 1979-1982;

² M. Marzi; D. Misiti Tetrahedron Lett. 30 (1989) 6075-6076;

³ A. Haines Carbohydrate Res. 1 (1965) 214-228;

⁴ N. Machinaga; C. Kibayashi J. Org. Chem. 57 (1992) 5178-5189;

⁵ M. Marzi; P. Minetti; D. Misiti Tetrahedron 48 (1992) 10127-10132;

Results of the asymmetric hydrogenation of prochiral substratesConditions: Substrate: Catalyst = 100:1, MeOH, 25° C., 1 bar of H₂;

t₁₀₀ % ee t₁₀₀ % ee t₁₀₀ % ee t₁₀₀ % ee t₁₀₀ % ee 18 n.b. 73.8(S) n.b.72.2(S)  3 h (98%) 75.0(R)  7 h (27%)  9.2(S) 48 h 20.8(R) 19  19 min94.8(S) 15 min 98.9(S) 20 min 96.9(R) 3 h 97.2(R)  4 h 78.8(R) 20 250min 91.5(S) 5 h 95.6(S) 17 h (94%) 81.5(R) 19 h (63%) 73.1(R)  7 h71.9(R)

We claim:
 1. A phospholane or diphospholane of the general formula I

where: R is H, C₁-C₆-alkyl, aryl, alkylaryl, SiR₃ ², R² is alkyl oraryl, A is H, C₁-C₆-alkyl, aryl, Cl or

B is a linker with 1-5 C atoms between the two P atoms.
 2. A phospholaneas claimed in claim 1, where R is H or CH₃.
 3. A diphospholane asclaimed in claim 1, wherein the substituents have the following meaning:

with n=0, 1, 2, 3, 4 or

with m=0, 1, 2, 3 R³=alkyl or fused aryl.
 4. A diphospholane as claimedin claim 3, wherein the substituents have the following meaning: m=0,n=1.
 5. A metal complex comprising a phospholane as claimed in any ofclaim 1 and a central atom selected from the group of Rh, Ru, Ir, Pd,Pt, Ni.
 6. A metal complex as claimed in claim 5, wherein Rh or Ru isselected as central atom.
 7. A process for the asymmetric hydrogenationof compounds by reacting the starting compounds to be hydrogenated withhydrogen in the presence of a metal complex as claimed in claim
 5. 8. Aprocess as claimed in claim 7, wherein the hydrogenation is carried outunder a pressure of from 1 to 2 bar of hydrogen.